/**
 * This jQuery plugin displays pagination links inside the selected elements.
 * 
 * This plugin needs at least jQuery 1.4.2
 *
 * @author Gabriel Birke (birke *at* d-scribe *dot* de)
 * @version 2.2
 * @param {int} maxentries Number of entries to paginate
 * @param {Object} opts Several options (see README for documentation)
 * @return {Object} jQuery Object

  .pagination .current {
            background: #e6e6e6;
        }
        .pagination a,
        #topage, .pagination span {
            display: block;
            float: left;
            height: 21px;
            padding: 0 5px;
            line-height: 21px;
            border: #c6c6c6 1px solid;
            background: white;
            text-align: center;
            margin-right: 3px;
            color: #333;
        }
 */
//define(function() {
    (function ($) {
        /**
         * @class Class for calculating pagination values
         */
        $.PaginationCalculator = function (maxentries, opts) {
            this.maxentries = maxentries;
            this.opts = opts;
        };

        $.extend($.PaginationCalculator.prototype, {
            /**
             * Calculate the maximum number of pages
             * @method
             * @returns {Number}
             */
            numPages: function () {
                return Math.ceil(this.maxentries / this.opts.items_per_page);
            },
            /**
             * Calculate start and end point of pagination links depending on 
             * current_page and num_display_entries.
             * @returns {Array}
             */
            getInterval: function (current_page) {
                var ne_half = Math.floor(this.opts.num_display_entries / 2);
                var np = this.numPages();
                var upper_limit = np - this.opts.num_display_entries;
                var start = current_page > ne_half ? Math.max(Math.min(current_page - ne_half, upper_limit), 0) : 0;
                var end = current_page > ne_half ? Math.min(current_page + ne_half + (this.opts.num_display_entries % 2), np) : Math.min(this.opts.num_display_entries, np);
                return { start: start, end: end };
            }
        });

        // Initialize jQuery object container for pagination renderers
        $.PaginationRenderers = {};

        /**
         * @class Default renderer for rendering pagination links
         */
        $.PaginationRenderers.defaultRenderer = function (maxentries, opts) {
            this.maxentries = maxentries;
            this.opts = opts;
            this.pc = new $.PaginationCalculator(maxentries, opts);
        };
        $.extend($.PaginationRenderers.defaultRenderer.prototype, {
            /**
             * Helper function for generating a single link (or a span tag if it's the current page)
             * @param {Number} page_id The page id for the new item
             * @param {Number} current_page 
             * @param {Object} appendopts Options for the new item: text and classes
             * @returns {jQuery} jQuery object containing the link
             */
            createLink: function (page_id, current_page, appendopts) {
                var lnk, np = this.pc.numPages();
                page_id = page_id < 0 ? 0 : (page_id < np ? page_id : np - 1); // Normalize page id to sane value
                appendopts = $.extend({ text: page_id + 1, classes: "" }, appendopts || {});
                if (page_id == current_page) {
                    lnk = $("<span class='current'>" + appendopts.text + "</span>");
                }
                else {
                    lnk = $("<a>" + appendopts.text + "</a>")
                        .attr('href', this.opts.link_to.replace(/__id__/, page_id));
                }
                if (appendopts.classes) { lnk.addClass(appendopts.classes); }
                if (appendopts.rel) { lnk.attr('rel', appendopts.rel); }
                lnk.data('page_id', page_id);
                return lnk;
            },
            // Generate a range of numeric links 
            appendRange: function (container, current_page, start, end, opts) {
                var i;
                for (i = start; i < end; i++) {
                    this.createLink(i, current_page, opts).appendTo(container);
                }
            },
            getLinks: function (current_page, eventHandler) {
                var begin, end,
                    interval = this.pc.getInterval(current_page),
                    np = this.pc.numPages(),
                    fragment = $("<div class='pagination'></div>");

                // Generate "Previous"-Link
                if (this.opts.prev_text && (current_page > 0 || this.opts.prev_show_always)) {
                    fragment.append(this.createLink(current_page - 1, current_page, { text: this.opts.prev_text, classes: "prev", rel: "prev" }));
                }
                // Generate starting points
                if (interval.start > 0 && this.opts.num_edge_entries > 0) {
                    end = Math.min(this.opts.num_edge_entries, interval.start);
                    this.appendRange(fragment, current_page, 0, end, { classes: 'sp' });
                    if (this.opts.num_edge_entries < interval.start && this.opts.ellipse_text) {
                        $("<span>" + this.opts.ellipse_text + "</span>").appendTo(fragment);
                    }
                }
                // Generate interval links
                this.appendRange(fragment, current_page, interval.start, interval.end);
                // Generate ending points
                if (interval.end < np && this.opts.num_edge_entries > 0) {
                    if (np - this.opts.num_edge_entries > interval.end && this.opts.ellipse_text) {
                        $("<span>" + this.opts.ellipse_text + "</span>").appendTo(fragment);
                    }
                    begin = Math.max(np - this.opts.num_edge_entries, interval.end);
                    this.appendRange(fragment, current_page, begin, np, { classes: 'ep' });

                }
                // Generate "Next"-Link
                if (this.opts.next_text && (current_page < np - 1 || this.opts.next_show_always)) {
                    fragment.append(this.createLink(current_page + 1, current_page, { text: this.opts.next_text, classes: "next", rel: "next" }));
                }
                $('a', fragment).click(eventHandler);
                return fragment;
            }
        });

        // Extend jQuery
        $.fn.pagination = function (maxentries, opts) {

            // Initialize options with default values
            opts = $.extend({
                items_per_page: 10,
                num_display_entries: 11,
                current_page: 0,
                num_edge_entries: 0,
                link_to: "#",
                prev_text: "Prev",
                next_text: "Next",
                ellipse_text: "...",
                prev_show_always: true,
                next_show_always: true,
                renderer: "defaultRenderer",
                show_if_single_page: false,
                load_first_page: true,
                callback: function () { return false; }
            }, opts || {});

            var containers = this,
                renderer, links, current_page;

            /**
             * This is the event handling function for the pagination links. 
             * @param {int} page_id The new page number
             */
            function paginationClickHandler(evt) {
                var links,
                    new_current_page = $(evt.target).data('page_id'),
                    continuePropagation = selectPage(new_current_page);
                if (!continuePropagation) {
                    evt.stopPropagation();
                }
                return continuePropagation;
            }

            /**
             * This is a utility function for the internal event handlers. 
             * It sets the new current page on the pagination container objects, 
             * generates a new HTMl fragment for the pagination links and calls
             * the callback function.
             */
            function selectPage(new_current_page) {
                // update the link display of a all containers
                containers.data('current_page', new_current_page);
                links = renderer.getLinks(new_current_page, paginationClickHandler);
                containers.empty();
                links.appendTo(containers);
                // call the callback and propagate the event if it does not return false
                var continuePropagation = opts.callback(new_current_page, containers);
                return continuePropagation;
            }

            // -----------------------------------
            // Initialize containers
            // -----------------------------------
            current_page = parseInt(opts.current_page, 10);
            containers.data('current_page', current_page);
            // Create a sane value for maxentries and items_per_page
            maxentries = (!maxentries || maxentries < 0) ? 1 : maxentries;
            opts.items_per_page = (!opts.items_per_page || opts.items_per_page < 0) ? 1 : opts.items_per_page;

            if (!$.PaginationRenderers[opts.renderer]) {
                throw new ReferenceError("Pagination renderer '" + opts.renderer + "' was not found in jQuery.PaginationRenderers object.");
            }
            renderer = new $.PaginationRenderers[opts.renderer](maxentries, opts);

            // Attach control events to the DOM elements
            var pc = new $.PaginationCalculator(maxentries, opts);
            var np = pc.numPages();
            containers.off('setPage').on('setPage', { numPages: np }, function (evt, page_id) {
                if (page_id >= 0 && page_id < evt.data.numPages) {
                    selectPage(page_id); return false;
                }
            });
            containers.off('prevPage').on('prevPage', function (evt) {
                var current_page = $(this).data('current_page');
                if (current_page > 0) {
                    selectPage(current_page - 1);
                }
                return false;
            });
            containers.off('nextPage').on('nextPage', { numPages: np }, function (evt) {
                var current_page = $(this).data('current_page');
                if (current_page < evt.data.numPages - 1) {
                    selectPage(current_page + 1);
                }
                return false;
            });
            containers.off('currentPage').on('currentPage', function () {
                var current_page = $(this).data('current_page');
                selectPage(current_page);
                return false;
            });

            // When all initialisation is done, draw the links
            links = renderer.getLinks(current_page, paginationClickHandler);
            containers.empty();
            if (np > 1 || opts.show_if_single_page) {
                links.appendTo(containers);
            }
            // call callback function
            if (opts.load_first_page) {
                opts.callback(current_page, containers);
            }
        }; // End of $.fn.pagination block

    })(jQuery);
//});
